I'm at 48.8mm from end of last spacer to the camera front edge, another 6.5mm to sensor plane, 55.3mm total. My sensor is the zwo1600, so only 21.9mm diagonal sensor. My thinking is that my sensor size might sit inside the well flattened area as shown by the curvature mapping on the stargazers lounge link (which is APS-C at 26.7mm diagonal).
And yep, I'll grab some with-withouts next time I have the newt out
